Hydraulic apparatus



June 16,- 1942 J, J, WA NER I HYDRAULIC APPARATUS I Filed Sept. 26', 1959 3 Sheets-Sheet 1 June 16, 1942. J WARNER 2,286,661

HYDRAULIC APPARATUS Fi led Sept. 26, 1939 s Sheets-Sheet s 5, xxx

mm ll l llllillllii Patented June s, 1942 UNITED) STATES, PATENT oFFicE mmiliiifilsm s iueafizt stptl gzg milita t: 290,004

2 Claims. (case-54.6)

invention relates to hydraulic apparatus wherein controlling or regulatory impulses are necessarily given at some distances from the location of the mechanism performing the work. One of the most serious defects in hydraulically operated mechanisms has been that variations in the volume of the liquid in the apparatus due to temperature changes are likely to impair the c f the a ratus. Another serious accum y pm 8-8 of Fig. 5, and

obstacle has been the constant danger that air may become entrapped with the liquid and resuit in uneven and variable transmission of efiective pressure. Accordingly, one object of my invention is to eliminate inaccuracies in the operation of hydraulic apparatus resulting from changes in the volume of the liquid, thereby adapting apparatus constructed according to my invention for use in vessels and aircraitwhere sudden and violent temperature changes are frequently encountered.

Another object of my invention is to provide means for drawing oil any air which may be-' come entrapped with the liquid in a hydraulic apparatus.

An important feature of my invention resides in a combination .of valves and conduits by means of which entrapped air can be withdrawn from the fluid, the combination of valves and conduits also servingto by-pass liquid from one side of the apparatus to the other to eliminate pressure diiferentials and to permit resetting of the controlling means relative to the work .performing mechanism.

, An important field of use for my invention is in marine steering gears in which rotation 35 of the steering wheel is arranged to deliver hydraulic impulses to the rudder or rudders. For

purposes of illustration I shall describe my invention as applied to a marine steering gear,

although it will be obvious to those skilled in the 40 2 is a view in front elevation of the con trolling -apparatus,

Fig. 3 is a view in cross section along the line 33 of Fig. 2,

Fig. 4 is a view in cross sectionalong the line 5 is a view in cross section taken vertically through the work performing mechanism,

Fig. 6 is a view in cross section along the line 6-6 of Fig. 5,

Fig. 'I is a view in cross section along theline 1-l of Fig. 5,

Fig. 8 is a view in cross section along the line Fig; 9 is a view in cross section along the line 9-9 0f P18. 5.

The general combination and arrangement of the elements forming my invention is best shown in Fig. .1 where it will be apparent that a fluidtight housing ill having opposed cylinders 28 and 29 is associated with a steering wheel it. These elements are designed to belocated in the forward part of a vessel, or in the wheel house, and are connected by conduits 39 and III to cylinders 44 associated with a fluid tight housing 46 disposed adjacent the rudder post in the stern of the vessel.

The details of the control mechanism are shown in Figs. 2-4 where it will be seen that the fluid-tight housing It! provides bearings for a transverse shaft l2 operating inside a sleeve l5 and carrying at its outer end a conventional steering wheel l3. Keyed on the shaft l2 inside the housing Ill is a pinion it which meshes with a large gear l8 keyed to a sleeve loosely carried by a stud i1 screwed into the rear wall of the housing Ill. Also keyed to the sleeve on the stud- I I is a pinion 20 which meshes with the teeth of a rack 26 supported. from below by a selfadjusting guide block 24 carried on a stud 22 screwed into the rear wall of the housing I 'in vertical alignment with the stud I1 and shaft 15. Screwed into the side walls of the housing I0 is a pair of oppositely disposed cylinders 28 and 29 which enclose pistons 30 carried on the ends of the rack 26. At theouter end of each piston -30 is a cup 32 of leather or other tough flexible material held against the outer surface of each piston by a washer 34 and a screw 36 which also serves to secure the piston to the end oi the rack.

Threaded on the ends of the cylinders 28 and 29 are cap fittings 38 each of which has an angular passage. Tapped into the bottom 0! the fittings are metal pipes or conduits and l 4 0 which serve as the pressure lines of the hydraulic system. As will hev seen from an inspection of Fig. 1, the lines 39 and 40 lead rearwardly in the vessel to thework performing 455 mechanism or the system, and it will be obl served that a crossovenis eiiected, that is to say, the line I! which leads from the left-hand cylin der 2! goes to the right-hand end of the work performing mechanism and that pressure line 40 which leads from the right-hand cylinder rudder post ind lower down than the control mechanis Therefore any air entrapped in the ends of the cylinders 44 or in pressure lines 39 and tel will rise and'enter the fittings. 30 on the 28 goes to the left side-of the work performing mechanism.

The work performing mechanisin is'similar to.

the controlling mechanism in its general features. a

It consists of a pair of oppositely disposed cylinders 44 provided at their outer ends with cap fittings 42 into the top of which the pressure lines ends of the cylinders 28 and 29. Each of the fittings 38 is provided with a small passage 82 into which is threaded a valve 04. Threaded into the valves '4 are by-pass pipes 86 which join in aT-shaped union 88 from which leads an outlet 80. The other end of the outlet 90 passes 1 into a valve 92 which leads into the housing l0.

3! and 40 are led in the manner stated above. The inner ends of the cylinders 44 arescrewed into the side walls of a metal housing 40 which lies in a horizontal. plane in contrast with the housing ll of the controlling mechanism which is in a vertical position.- A rack 48 operates ili the housing 46 and in' the cylinders 44, being guided in its movement by a block 50 carried on a stud 52 screwed into the bottom of the housing 44. On' each end of the rack 48 is a piston 54 provided with a leather cup .56 secured to the" i outer end of each piston by a washer 51 and a screw which does-not, however, enter the rack 48. The ends of the rack are reduced and mounted to slide in apertures in the pistons 54. The pistons 54 are slotted asshown in Fig. 8 and locking pins 60 passed through the ends of the rack 48 operate in the slots in the pistons 54, thus allowing limited relative longitudinal movement between the rack and the pistons. Powerful coil springs 02 encompass the reduced portion of the rack 44, the inner ends of the pisthus 54 being recessed to provide a tubular skirt for housing them. Heavy washers 64 serve to back up the springs 8!, audit will be apparent that the springs 82 urge the pistons 54 outwardly on the rack 4|. 1 v

In mesh with the teethof the rack 4i and within the housing 44 is a large gear OI which is keyed to'a vertical shaft .88 iournaled in the housing 46 and extending up through the upper wall thereof. Rigidlysecured to the upper end of the shaft 88 is an arm whichis pivotally connected at its outer end to an elongated link The housing It is provided with a removable filling plug ll having a small passage or jet 94 communicating with the outside of the housing.

It will now be apparent that if in the course of operation the system should build up more pressure on one side than the other, the valves 84 can be opened and the by-pass 86 will allow the pressures to equalize. If there is air in the system the valve 92 can also be opened, and since it is in direct. communication with the lines 39 and and is the highest point in the conduit systam, the entrapped air will rise and pass through the lines 86 into the outlet 90, through the valve 92 into the housing It and out through the passage 94 in the fill plug II. It will also be evi-, dent that the easiest way to fill the system with oil or other liquid is'to open the valves 84 and the valve 92 so that the liquid will fiow directly into the lines 39 and" as well as into the=housing it. .The housing 48,is provided with a filling plug I6 and can be filled directly.

It should be observed that the function of the leather cups 5! and 32 is to act as one-way valves. That is to say, when a piston is being pushed outwardly in a cylinder its associated leather cup will open and prevent the passage of liquid by the piston. When the piston is being withdrawn into the cylinder the cup will tend to fold up so that some liquid can flow past the piston from within the housing. The leather cups, therefore, insure smooth and efficient op- I2. The link I! is pivotally connected to a tiller I4 which in turn is rigidly secured to the rudder post I! as shownin Fig. 1.

The operation of the parts thus far described can be briefly stated. The entire system including the housings l0 and 48 is filled with oil or other liquid suitable for use in an hydraulic system, and when this has beendone, it will be apparent that if the wheel is rotated in counter-clockwise direction, the pisto'n 30 in the cylinder 2! will be moved outwardly, toward the left, forcing oil through theline 39 and into the righthand cylinder 44 where the piston in the cylinder will be forced inwardly, moving the rack 48, rotating the gear 66,'and moving the arm "to the left, thus swinging the tiller [4 to the left and causing the vessel to swing to the left. If the wheel I! is rotated in clockwise direction the piston, the cylinder 28 will force oil through the line 40 to actuate the rack 48' and the gear 8! which will, in the manner already described, swing the tiller [4 to the right, thus swinging the vessel in the same direction.

As shown in Fig. 9 each of the cap fittings 42 is provided at its upper end with a small passage leading from the cylinder to the pressure line and serving to remove air entrapped in the top of the cylinder. It is contemplated that the work performing mechanism will be located near the eration since all of the pressure exerted by a piston in its outward stroke will be utilized whereas pressure behind the piston will not interrupt its inward movement by reason of the fact that a back pressure can be relieved by the passage of liquid by the piston and its associated leather cup. It is important to note that both the housing It and the housing 48 are designed to be entirely filled with the hydraulic fiuid, a feature which materially reduces the likelihood of air becoming entrapped in the system. I

In particular, it is to be noted that in a heavy sea a wave often slams against the rudder pushing it to one side and thus moving the pistons in the cylinders 44 and spinning the steering wheel. If the housing 48 were not filled with fluid, air would be sucked into the one, of the cylinders 44 whenever a wave hit the rudder,'thus hindering the smooth accurate operation of the system, since part -pf the air would work by the leather cups and into the pressure lines.

The combination of the locking pins 60, the slots in the pistons 54, and the springs 82 operates to compensate for changes in the volume of the liquid in the system due to changes in temperature. That is to say, a reduction in the volume of the liquid due to cold weather will cause the'fiuid in the housings l0 and 46 to pass by the leather cups on the ends of the pistons, whereas an increase in the volume of the liquid due to hot weather will press the pistons 54 inwardly in the cylinders 44 and compress the spring 82,

duits 39 g and 40 is much more subject to expansion and contraction due to its surface area than the liquid in the body of either of the housings.

The particular .advantages resulting from the use of my invention arise because I have reduced the possibility of entrapped air by filling both housings with fluid and arranged for its escape through the conduits 86 and 90, the fact that pressure diiierentials can be eliminated by ,opening the valves 84, and because I' have provided means which compensate for any changes in the volume of the liquid in the system. I

It should further be understood that by opening the valves 84 and moving the tiller I4 until it is parallel with the longitudinal axis of the vessel, the relative positions of the rudderand the pistons can be set, thus allowing the king spoke of the steering wheel to be set vertically when the rudder is in normal position and insuring equal movement thereof in either direction.

While the invention has been described as applied to apparatus for steering vessels, it must be understood that with very slight modifications the system shown in the drawings can be adapted to control the rudder and ailerons of an airplane. It can also be adapted to steer an automobile or truck or, indeed, it is useful wherever it is desirable to separate work performing mechanism from controlling mechanism. The system illustrated in the drawings may, with slight modifications, be operated to control valves of a large automatic pressure pump in order to steer aheavy vessel or ship where power is necessary to move the rudder.

Having thus disclosed my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a hydraulic system, a housing,'a pair of cylinders secured in the walls of said housing, a

rack disppsed in the housing and having reduced shouldered ends extending into said cylinders, a

pin secured in each of said reduced ends, a piston in each cylinder having a central longitudinal bore receiving the end of the rack and a slot accommodating the pin, the inner end of each piston being provided with a tubular skirt, a spring disposed within the skirt of each piston and surrounding a portion of the reduced and of the rack, and a washer surrounding the reduced end of each rack and held against the shoulder onthe rack.

'2. In a hydraulic steering system for vessels, a

housing, a pair of cylinders secured in the walls of said housing, a rack disposed in the housing within the skirt or each piston and surrounding a portion oi the end 01' the rack, whereby expansion of fluid in the system is compensated for by the opposite movement of the pistons with out changing the position of the rack.

JOSEPH J. WARNER. 

